1. Field of the Invention
The present invention relates to a peg for a stringed instrument (for example, a guitar). In particular, the present invention relates to a technique in which a center of a winding shaft is concentric with respect to that of a hole in a head of a stringed instrument.
2. Description of the Related Art
A stringed instrument (for example, a guitar) is equipped with a peg for tuning a string. As shown in FIG. 11, the peg is equipped with a main body 110, a worm gear 120, a knob 130, a winding shaft 140, and a worm wheel 150. The worm gear 120 is rotatably supported by the main body 110. The knob 130 is secured at an end portion of the worm gear 120. The winding shaft 140 is rotatably supported by the main body 110. The worm wheel 150 is connected to an end portion of the winding shaft 140, and engages with the worm gear 120.
The above peg 100 is mounted to a head 200 of a stringed instrument such that the winding shaft 140 penetrates a hole 200a formed in the head 200, a winding surface 141 of the winding shaft 140 is projected from the hole 200a, the main body 110 is secured on a lower surface of the head 200 by a screw (not shown in the Figure). A string is wound around the winding shaft 140, and the string is wound therearound or released therefrom by rotating the knob 130, so that tuning of the stringed instrument is performed. A guide bush (not shown in the Figure) is fitted into the hole 200a from an upper surface of the head 200, and a screw (not shown in the Figure) is tightened in an inside periphery of a guide tube 110a, the screw being formed on a small diameter periphery at a front end of the guide bush. As a result, the winding shaft 140 is rotatably supported by the main body 110 and the guide bush, and the main body 110 is secured to the head 200.
In the above peg 100, for example, the guide tube 110a is formed by die casting to be integrally combined with the main body 110. The guide tube 110a is fitted into the hole 200a of the head 200, so that a center of the winding shaft 140 is concentric with respect to that of the hole 200a. For example, a peg constructed in the above manner is disclosed in Japanese Unexamined Patent Application Publication No. S59-184395.
In addition to a peg of which the main body is produced in the above manner, a conventional type of peg having no guide tube is widely used in which a main body thereof is formed by performing press-working on a metal plate. In a case in which this type of peg is mounted to a head, first, a guide bush is press-fitted into a hole from an upper side of the head. Next, a winding shaft of the peg is inserted into the hole from a lower side of the head, and is fitted inside the guide bush. Next, a screw penetrates through a mounting hole formed in the main body, and is tightened into a hole formed in the head, so that the main body is mounted to the head. However, since clearance exists between the winding shaft and the guide bush, when a worker aligns the winding shaft with a center of the guide bush, the aligning of the winding shaft largely depends on the judgment of the worker. Since clearance exists between the mounting hole of the main body and the screw penetrating thereinto, the main body shifts from its predetermined mounting position with respect to the head. When the screw is tightened into the hole of the head, the screw is not often inserted straight thereinto. As described above, there are various cases in which the above location shift of the main body occurs when the peg is mounted to the head. As a result, the center position of the peg is eccentric with respect to that of the guide bush, so that the winding shaft is disposed so as to abut the inside wall of the guide bush.
In a peg proposed previously by the inventors in WO Patent Application Publication No. WO02/091350A1, PCT/JP01/03798, a worm wheel is rotated by tension of string, a tooth surface on one side of the worm wheel constantly abuts a toothed wheel on one side of a worm gear. Therefore, since this peg has no play which occurs due to backlash, the worm wheel accurately follows rotation of a knob, and tuning of a stringed instrument can be performed accurately and easily. However, in a case in which the winding shaft is disposed to abut the inside wall of the guide bush as described above, rotational frictional resistance of the winding shaft is large, and the worm wheel cannot be rotated by the tension of the string, so that the backlash functions as play of the rotation. Unusual force is applied to the tooth surfaces of the worm wheel and the worm gear which abut each other, and these parts are thereby soon become worn.